Changing a value node in many materials with a python script
The script below iterates over all selected objects and adjusts the value nodes in the assigned materials if their label is set to &quot;Scale&quot;.
import bpy
      
       
def set_scale_nodes_selected_objects(scale_val):
    for obj in bpy.context.selected_objects:
        for mat_slot in obj.material_slots:
            set_scale_nodes_material(mat_slot.material, scale_val)
    

def set_scale_nodes_material(mat, scale_val):
    if mat is not None and mat.use_nodes and mat.node_tree is not None:
        for node in mat.node_tree.nodes:
            if node.label == &quot;Scale&quot; and node.type == &quot;VALUE&quot;:
                node.outputs[&quot;Value&quot;].default_value = scale_val  


if __name__ == &quot;__main__&quot;:
    scale_val = 1.0
    set_scale_nodes_selected_objects(scale_val)